1. Field of the Invention
The present invention relates to a method of producing a high-strength cold-rolled steel sheet which excels in workability and which is free from the problem of P segregation zone which is produced when a large amount of P is added for the purpose of enhancing the strength of the steel sheet.
In recent years, there is an increasing demand for high-strength steel sheets in the field of automobile production, in order to meet current requirements for reduction in the weight of automobiles to attain a higher fuel economy and for ensuring safety of drivers and passengers.
In modern automobile production, high-strength cold-rolled steel sheets are used not only for the inner panels but also for outer panels such as engine hoods, trunk lid and fenders. As a consequence, high-strength cold-rolled steel sheet is required to have an excellent workability.